The renin-angiotensin-aldosterone-system and left ventricular mass in young black and white adults: the African-PREDICT study

Abstract

Motivation. The renin-angiotensin system (RAS) is a central regulatory component implicated in sodium and water homeostasis that affects blood volume and pressure. Dysregulation of this system results in increased blood pressure (BP) and may contribute to the development of left ventricular hypertrophy (LVH). In addition to the RAS and BP, factors such as increased age, sex, black ethnicity and a low socio-economic status (SES) also contribute to left ventricular remodelling. In the South African context low SES may be even more important as it affects 55.5% of the population with a large proportion (63.4%) of them being young and unemployed. It is therefore important to investigate RAS-related increases in left ventricular mass (LVM) along with the possible influence low SES may have in young South Africans. Aim. This study investigated the relationship between LVMi (index) and the RAS components in young (20-30 years) healthy participants of the African-PREDICT study while taking factors such as SES, ethnicity and sex into consideration. Methods. This study used cross-sectional data from 1 186 black and white men and women divided into low and high SES groups. Demographic data including age, sex, ethnicity, skill level (classified according to the South African Standard Classification of Occupation (SASCO), education and income were collected using various questionnaires. Socio-economic status was calculated using a point system adapted from the Kuppuswamy's Socioeconomic Status Scale. Anthropometric measurements and physical activity were measured. Cardiovascular measurements included clinic BP, 24h ambulatory BP, total peripheral resistance and echocardiography which were used to determine LVM - normalised for body surface area to derive LVMi. The RAS Fingerprint® was measured with an ultra-pressure-liquid chromatography tandem-mass spectrometry (LC-MS/MS) method. A wide range of other biochemical markers considered as cardiovascular disease risk markers were also analysed. Results. Aligned with the aim of this study it was determined whether LVMi is associated with components of the RAS. LVMi associated inversely and independently with plasma renin activity (ꞵ=-0.168; P=0.017), angiotensin I (ꞵ=-0.155; P=0.028) and angiotensin II (ꞵ=-0.172; P=0.015), only in black women with low SES. No associations were evident between LVMi and components of the RAS in black women with high SES, or white women, black or white men, independent of SES. Conclusion. This finding suggests that multiple factors may play a role in the development of increased LVM, including suppressed RAS, raised BP, female sex, black ethnicity and a low socio-economic environment.